Such hand tools are described in the journal test, 11/88, pp. 90-95 (or continuous page numbers 1106 to 1111). The motor is driven by the built-in battery. Thus, work is not encumbered by an electrical cord.
The output of such tools is limited by the electrical voltage of the battery used. In actual practice rated voltages of 4.8V to 9.6V are employed. High voltages are desirable to increase output. However, this results in the disadvantage that with higher voltages the batteries are correspondingly larger, so that the design of the tool becomes awkward.
Cylindrical batteries, oval in cross section, are used in conventional screwdrivers. Their length is dependent upon the rated voltage. The battery is inserted from below into the handle component. With batteries of higher rated value, the handle component is awkward in its length. In other screwdrivers the battery is shoved into the drive component from behind. Accordingly, the drive component is then of awkward length.
In other conventional power screwdrivers, block-shaped batteries are used, which are located in the lower part of the handle component and extend beyond it. This design, as well, appears to be awkward.
With conventional models, besides the battery, the switch, as well, is located in the handle component. Thereby, the space available to the battery in the handle component is limited.
In West German GM No. 85 05 814 such a screwdriver is described in which the battery and the switch are located in the handle component.